Project Summary Anterior cervical fusion surgery effectively restores function and alleviates pain due to degenerative spine disease. However, the degeneration of motion segments adjacent to the fused cervical vertebrae (adjacent segment disease) is a concern for patients and surgeons. It has been proposed that mechanical factors, including excessive stress applied to adjacent motion segments, drive the progression of adjacent segment disease. Improved understanding of these mechanical factors associated with adjacent segment disease can best be obtained through collecting data in vivo during a variety of functional loading tasks. We propose to study the effects of cervical fusion on adjacent segment motion using a unique biplane radiographic imaging system capable of characterizing in vivo motion during functional loading. The biplane radiographic system will collect x-ray data at 50 frames per second as subjects perform cervical flexion/extension, lateral bending and axial rotation movements. Three-dimensional bone motion will be accurately measured using both a dynamic RSA technique (bead-based tracking) and a validated markerless technique (model-based tracking). Anterior cervical fusion subjects will perform movement tests two times following surgery (6-9 months and 24 months post-surgery) to assess changes in overall vertebral motion (bone kinematics) and changes in relative motion between vertebral endplates (arthrokinematics) over time. Data collection during movement will allow us to quantify the dynamic stability/instability of the cervical spine throughout the range of motion. Arthrokinematic measurements of vertebral endplates will allow us to infer mechanical loading conditions applied to intervertebral discs (compression, shear, torsion) during functional loading. Fusion subject's vertebral movements will be compared to asymptomatic, age-matched control subject's vertebral movements. The proposed study will be the first to record precise, three-dimensional, in vivo movement of cervical vertebrae in asymptomatic subjects and anterior fusion patients. The first aim of the study is to identify specific kinematic and arthrokinematic measurements that differentiate between asymptomatic subjects and single- level anterior fusion patients during in vivo functional loading. The second aim is to identify changes in cervical vertebrae kinematics and arthrokinematics over time in the fusion patients. Finally, changes in fusion group kinematics and arthrokinematics will be correlated with patient outcome survey results and standard clinical measures of degenerative disc disease/spinal instability in order to relate abnormal vertebral movement to patient symptoms and clinical findings. Knowledge acquired from this study may lead to improved diagnosis and treatment for patients afflicted with degenerative spine disease. PUBLIC HEALTH RELAVANCE: Project Narrative It has been reported that between 16% (Ishihara, 2004) and 25% (Hilibrand, 1999) of patients who have surgery to alleviate degenerative spine disease have new disease within 10 years of the operation. Abnormal spine movement following surgery may increase stress on adjacent portions of the spine and cause further spine degeneration. This project aims to identify abnormal neck bone movement that may be associated with degenerative spine disease following spine surgery.